1. Field of the Invention
The present invention relates to an electronic level in which a light compensated by a compensator provided inside a telescope is received by an image sensor and a horizontal sighting position code is obtained by computation.
2. Description of the Related Art
As this kind of electronic level, there has been known the following in Japanese Published Unexamined Patent Application No. 4959/1995. Namely, the light which is incident from an objective lens is passed through a compensator. The light is thereafter introduced into an image sensor and is converted into an image signal. The image signal is then captured by (or taken in) a computation section to thereby compute the height of the horizontal sighting position code.
As is well known, the compensator is provided with reflecting mirrors which are swingably hung by a hanging wire. The light which is incident from the objective lens is once reflected by the reflecting mirrors. In this manner, even if the telescope is inclined in the up and down direction (i.e., relative to an optical axis of the telescope), the inclination of the telescope is compensated by the automatic inclination of the reflecting mirrors by an amount in proportion to the inclination of the telescope.
Since the above-described conventional electronic level is provided with a compensator, if the telescope swings, the reflecting mirrors of the compensator also swing. As a result, the light to reach the image sensor thereby becomes an unstable condition. Then, depending on the timing in which the computing section captures the image signal, the image signal of the position that is away from the position to be collimated horizontally will be captured. There is therefore a possibility that the error of the collimated position to be computed becomes extremely large. In such a case, the following solution may be considered. Namely, the time (or duration) in which the computation section captures the image signal is extended or the number (or frequency) of capturing is increased to thereby increase the number of image signals to be captured by the computation section. However, this solution is not preferable because unnecessarily long time is required for capturing the image signals even when the reflecting mirror does not swing.
In view of the above points, the present invention has an object of providing an electronic level in which an error in the computing results due to swinging can be minimized without unnecessarily extending the measuring time.
In order to attain the above and other objects, according to one aspect of the present invention, there is provided an electronic level in which light incident from an objective lens is passed through a compensator and is introduced into an image sensor to convert it to an image signal, the image signal being captured by a computing processing section to thereby compute a horizontal collimation position. The electronic level comprises vibration detecting means provided inside a main body of the electronic level, wherein number of captured image signals by the computing processing section is varied to increase or decrease depending on the magnitude of compensator mirror amplitude of vibrations detected by the vibration detecting means.
According to another aspect of the present invention, there is provided an electronic level in which light incident from an objective lens is passed through a compensator and is introduced into an image sensor to convert it to an image signal, the image signal being captured by a computing processing section to thereby compute a horizontal collimation position. The electronic level comprises vibration detecting means provided inside a main body of the electronic level, wherein the cycle of captured image signals by the computing processing section is varied to be long or short depending on the length of compensation mirror cycles of vibrations detected by the vibration detecting means.
According to still another aspect of the present invention, there is provided an electronic level in which light incident from an objective lens is passed through a compensator and is introduced into an image sensor to convert it to an image signal, the image signal being captured by a computing processing section to thereby compute a horizontal collimation position. The electronic level comprises: vibration detecting means provided inside a main body of the electronic level; and indicating means to indicate that the computation in the computing processing section cannot be performed when vibrating state to be detected by the vibration detecting means has exceeded a predetermined limit state.
By providing the vibration detecting means, the vibrations actually operating on the electronic level are detected. When the amplitude of the vibrations is large, the number of captured image signals by the computing processing section is increased to thereby minimize the error due to the operation of the vibrations. On the other hand, if the amplitude of the vibrations is small and if there is no possibility of occurrence of an error due to the vibrations, the number of captured image signals by the computing processing section is reduced to thereby shorten the time required for measuring.
If the amplitude of the vibrations which operate on the electronic level does not vary, there is no need of increasing or decreasing the number of capturing the image signal by the computing processing section. If the period of vibrations is short, the measuring accuracy does not change even if the number of capturing the image signal by the computing processing section is shortened depending on the period of the vibrations. In this manner, if the period of capturing the image signal is shortened, the time required to obtain the measuring result can be shortened. On the other hand, if the period of vibrations is long, it is necessary to extend the period of capturing the image signal. As a result, the time until the measuring result can be obtained becomes longer. However, as compared with the conventional art in which the period of capturing the image signal is not changed so as to become longer, the measuring accuracy of the present invention can be improved.
In case the conditions of vibrations which operate on the electronic level, e.g., the amplitude and the period, exceed a predetermined limit state which is set as a limit beyond which measuring cannot be made, the measured result will not be indicated or, even if indicated, the values indicated are not reliable. However, until a considerable time has passed, it is difficult to judge whether the above-described state is present or not. As a solution, when the vibration state to be detected by the detecting means has exceeded a predetermined state, an indication is immediately made to that effect without performing the computation.
As the vibration detecting means, a telescope may be separately provided with a vibration sensor. However, the vibration detecting means may be constituted by a light irradiating section to irradiate light to a reflecting mirror of the compensator, and a line sensor which receives the light irradiated from the light irradiating section and reflected by the reflecting mirror. In a state in which the reflecting mirror is swinging, the position in which the light reaches the line sensor varies Therefore, the vibration state of the reflecting mirror can thus be detected.
If the reflecting mirror is swinging, the image to reach the image sensor swings. Therefore, the state of swinging can be detected from the image signal.